Autonomic Nervous System

Question 1

Function divisions of the nervous system:

Sensory is ? - two subdivisions?

Motor is ? - two subdivisions?

Answer 1

Sensory is afferent - somatic (body wall structures) and visceral (organs, blood vessels)

Motor is efferent - somatic (voluntary muscles) and autonomic (ANS- sympathetic and parasympathetic)

Question 2

Difference in neuron systems between somatic motor system and ANS

Answer 2

Somatic motor system is a one neuron system; ANS is two neuron

Sympathetic has long post ganglionic neurons; parasympathetic has very short post ganglionic neurons and use one neurotransmitter

Question 3

Where do sympathetics emerge from?

Parasympathetics?

Answer 3

Sympathetic = T1-L2

Parasympathetic - S2-S4 and cranial nerves: head and neck (CN III, VII, IX) and body (CN X)

Question 4

1. Sympathetics go through __ nerves (be specific)

2. Parasympathetics go through ___

Answer 4

1. Spinal nerves; every spinal nerve dorsal and ventral ramus carries sympathetics
2. Cranial nerves

Question 5

What kind of innervation is body wall structures?

Answer 5

Sympathetic

Question 6

What are the three divisions of the gray matter of the spinal cord?

Where are the preganglionic sympathetic cell bodies housed?

Answer 6

~Gray matter is inner, butterfly shaped part of spinal cord~

Anterior, intermediolateral, and posterior column

In the intermediolateral column

Question 7

General pathway of spinal nerve sympathetics?

Answer 7

1. Emerge from T1-L2 spinal levels
2. Preganglionic axons enter sympathetic ganglion through white Ramus communicans (myelinated)
3. Paravertebral sympathetic ganglion
4. Synapse
5. Post ganglionic axons exit through gray ramus communicans
6. Travel with dorsal or ventral ramus to target

Question 8

How does the sympathetic chain supply structures such as the head, abdomen, and limbs (which are not innervated by T1-L2)

Answer 8

Preganglionic axons can travel superiorly and inferiorly along sympathetic chain before synapsing

Question 9

Parasympathetic and sympathetic innervation of internal organs superior to the diaphragm?

Answer 9

Para- Vagus (CN X)

Sympathetic- T2-T5 spinal levels; thoracic sympathetic nerve

Question 10

Where do thoracic parasympathetic preganglionic fibers synapse?

Answer 10

On the target organs

Question 11

Broad pathway of thoracic sympathetic nerves

Answer 11

1. Emerge from T2-T5 spinal levels
2. Travel to sympathetic ganglion
3. (Optional) travel through sympathetic chain
4. Synapse
5. Post ganglionic axon leaves ganglion for organ

Question 12

Parasympathetics that innervate the internal organs of the abdominal and pelvic regions?

Sympathetic?

Answer 12

Vagus (CN X) and Pelvic splanchnic nerve (S2-S4)

Greater splanchnic nerve (T5-T9), lesser splanchnic nerve (T10-T11), least splanchnic nerve (T12), lumbar splanchnic nerve (L1-L2)

Question 13

Pathway of splanchnic nerve

Answer 13

1. Emerge from T5-L2 spinal levels
2. Travel to sympathetic ganglion
3. (Optional) travel through sympathetic chain
4. DO NOT synapse
5. Preganglionic axon leaves for subdiaphragmatic ganglion (splanchnic nerve)
6. Synapse (on subdiaphragmagtic ganglion)
7. Travel to organ

Question 14

Post ganglionic fibers follow vessels to abdominal organs except?

Answer 14

The suprarenal gland -receives preganglionic sympathetic axons that synapse on the gland itself

Question 15

Visceral pain follows the path of sympathetic efferents except?

Answer 15

They got through dorsal root, not ventral root
Also they don’t synapse until they reach the spinal cord
(Only sympathetics can carry pain afferents)

Question 16

If you have gallbladder inflammation, it causes pain in two places: __ and ___. Why?

Answer 16

Diaphragm and shoulder

When gallbladder gets irritated, it also irritates diaphragm because they are touching each other. C3-C5 innervate the diaphragm, and the dermatomes for these nerves is located at the shoulder

Question 17

Discomfort in pelvic organs due to full bladder, rectum, or uterine cervix are transmitted through?

Answer 17

PARAsympathetic pelvic splanchnic nerve (no sympathetic ganglion involved)
This is exception because usually visceral pain goes through sympathetic)

Question 18

Nerves that synapse at the same spinal level travel through?

Answer 18

White ramus communicans - (then synapse at sympathetic ganglion aka paravertebral ganglion) - gray ramus communicans

Question 19

How does the splanchnic nerve travel

Answer 19

It goes from lateral horn, thru ventral root, enter white ramus communicans, then synapses at the sympathetic/paravertebral ganglion, then leaves by its own nerve (so doesnt go through gray ramus communicans

Question 20

Some preganglionic fibers bypass the sympathetic/paravertebral ganglion completely … what happens?

Answer 20

They go through white ramus communicans then leave and they synapse in a peripheral ganglion near the target organ

Question 21

How do you get sympathetic innervation to head/neck for example?

Answer 21

Enter through the white ramus communicans but do not synapse at that sympathetic/paravertebral ganglion; they ascend (can also descend for other areas of the body) and synapse at a different level

Question 22

Two types of splanchnic nerves and how do they synapse?

Answer 22

Post ganglionic splanchnic- synapse at the sympathetic/paravertebral ganglion, then have a post ganglionic neuron that leaves by its own nerve

Preganglionic splanchnic- bypasses sympathetic ganglion to form a synapse in a peripheral ganglion